On-board diesel oil and water emulsification system

ABSTRACT

A fuel system for feeding a non-stable emulsified fuel to a diesel engine, the improvement comprising a non-stable oil-in-water emulsion in which at least 90 percent of the droplets are less than 1 micrometer in diameter and the mixing chamber is positioned in relatively close proximity to the diesel engine such that the emulsion does not substantially de-emulsify between the mixing chamber and the diesel engine.

FIELD OF THE INVENTION

The invention refers to an emulsified fuel and more particularly to anemulsified fuel of diesel oil-in-water with or without the use of asurfactant.

BACKGROUND OF THE INVENTION

The impact of diesel fuels both environmentally and with regard to airpollution has been the subject of considerable research and patentmatter. The main air pollutants from diesel engine exhaust gas arecarbon monoxide (CO), nitrogen oxides (NO_(x)), carbon dioxide (CO₂),hydrocarbons and particulate matter. The specific composition ofemulsions is important to the fuel industry with regard to the stabilityof the emulsion, namely usefulness during transportation and the variouscontaminants which may effect the stability of the emulsion followingthe use of additives during operation.

It is well known in the industry that NO_(x) emissions from dieselengines are reduced by mixing water in the diesel fuel which in turnreduces combustion temperatures. The emulsified fuel optimizescombustion by which, in turn, reduces nitrogen oxides, the major causeof air pollution. In this regard, moisture in the form of particles ishomogeneously contained in the emulsified fuel, the fuel limits thegeneration of high temperatures in local areas in the flame and further,20 to 30 volume % of moisture lowers the combustion temperature,primarily through latent heat of evaporation. Therefore the emulsifiedfuel limits the generation of nitrogen oxides by preventing hightemperatures in local areas. The water is proportionately mixed into thediesel fuel and the mixture is injected into the cylinders. When wateris added to the fuel, one of the two liquids disperses into the otherliquid, and emulsion occurs thereby. Since the appropriately mixedemulsion is formed in a stable condition, the separation between waterand fuel before combustion is not in issue. However, an anionicsurfactant is usually present in the water to enhance dispersion andpermeation of the chemicals which are added together with the water. Thedisadvantage of introducing a surfactant is the penalizing factortowards engine performance characteristics.

An emulsified fuel is typically prepared by mixing the fuel with a watermixture containing a surfactant, for example, mixtures of naturalsurfactants such as sulfates, sulphonates and carboxylates, or the like.The use of surfactant allows for small, medium or large systems tooperate without any control means to constantly maintain the optimalratio of combustible fuel to water.

With the use of surfactants, the engine will continuously incur powerloss penalty resulting from the addition of water to the fuel mixture asfuel has no potential for thermal energy. Further during coldtemperature operations, the water content is a concern for fuel flow andexhaust emission reduction potential is minimized.

Fuel emulsification based on diesel fuel+water+surfactant is presentlybeing demonstrated in a number of different mobile source fleets, as ameans of reducing oxides of nitrogen. Test results have indicatedreductions in oxides of nitrogen ranging from 15 to 30%, particulatereductions from 0 to 30% and power losses in the range of 10 to 15%.

For applications where a loss in power for some activities is not anoption or cold temperature is a concern for fuel flow, theemulsification technology using a surfactant is not an option forexhaust emissions reduction.

U.S. Pat. No. 6,211,251 discloses a known type of fluid emulsificationsystem having primary and secondary fluids. The fluids are delivered byinjectors to combine an air-fuel mixture in an emulsion tube whichincludes obstructions to assist in emulsifying the mixture. Thedifficulty to be overcome by the present invention being that the wateradded to such an emulsification system that is not combusted by theengine will result in premature corrosion of the cylinders and variousother components of the engine. Thus, the life of the engine issignificantly reduced.

The purpose of the invention is therefore to provide a system whichallows for the same oxides reductions based on the use of a surfactantwith the additional flexibility to allow the diesel engine (such as anon-board engine in a marine vessel) to achieve full power in criticalsituations.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a fuelsystem for feeding fuel to a diesel engine, particularly a means forvariably feeding an excess of a non-stable emulsion of blending agent indiesel fuel to said diesel engine, recovery means for recovering excessfuel fed to the diesel engine, and separating means associated with therecovery means for separating of the recovered non-combusted fuel intoits component parts.

It is desirable the above further includes a means for blending aplurality of blending agents.

Desirably, the above includes an emulsifier means for forming anon-stable water in oil emulsion in which at least 90% of the dropletsare less than 1 um in diameter, and the system comprises a water source,a diesel oil source and a mixing chamber having an agitation means forforming the non-stable emulsion mixture, the first and second sourcesinclude a signal means and a pump means.

Preferably, the agitation means is a propeller capable of havingrevolutions of 2500 to 6000 RPM, the recovery means comprises anon-stable emulsification of blending agent and diesel oil separatinginto its separate components and a recovery chamber having one or morechannels, and the system is an on-board system.

In a preferred embodiment of the above, one of the channels recoverdiesel oil from said non-stable emulsification of blending agent anddiesel oil.

In another embodiment of the present invention, there is provided aclosed loop system for feeding fuel to a diesel engine having the aboveembodiments and the closed loop including a source of diesel oil, asource of blending agent, valve means for controlling fluid flow fromthe source of water, a mixing chamber having agitation means for formingan emulsion mixture, a microprocessor means for controlling the valvemeans and fluid flow a diesel engine, the separating means includes adiesel return flow and a blending agent return flow, the water returnflow being operatively associated with the source of blending agent, andthe diesel return flow being associated with the source of diesel oil.

It is also a preferred embodiment of the present invention wherein amethod of feeding fuel to a diesel engine in a closed loop systemincludes the steps of:

-   forming of a variable non-stable emulsion comprised of a blending    agent and diesel fuel,-   feeding an excess of the non-stable emulsion to a diesel engine,-   separating the excess amount into the component parts of the    emulsion, and-   recovering excess amounts of the emulsion not combusted by said    engine.

Further in a preferred embodiment of the above, the above steps includethe system comprising a mixing chamber having an agitation means, thefirst and second sources include a signal means and a pump means, theagitation means is a propeller having revolutions of 2500 to 6000 RPM,the recovery means comprises an non-stable emulsification of water anddiesel oil separating into its separate components and a recoverychamber having one or more channels, and system is an on-board system.

Moreover, a further preferred embodiment, one of the channels recoversdiesel oil from the non-stable emulsification of water and diesel oil.

It should be noted that more than one nozzle may be used to provide morethan one blending agent to be mixed into the emulsion.

In the above embodiments, it is further preferable the system is anon-board system.

Having thus, generally described the invention, reference will now bemade to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a system in a preferred embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE DRAWINGS

The overall system of the present invention is designated by thereference numeral 100, and includes a continuous loop or closed circuitoperation, for use of a non-stable emulsion of water-in-diesel fuel as afeed for fuel to a diesel engine 40 such as those used in a marinevessel. In the system 100, a water source 20 is connected to a meteringdevice 23, such as a proportional control valve, which meters the flowof the water volume to be mixed.

The diesel oil source 10 and the water source 20 are each fed to amixing chamber 30 through feed pipes 15 and 17 by pumps 25 and 27. Inanother embodiment of the present invention, where it is desired to useminor amounts of a surfactant for the emulsion system otherwise usedherein it will be understood that a suitable source of surfactant may beprovided and likewise, a proportional control valve may be used to meterthe amount of surfactant for Use in the present invention.

The blending agent is then added to the fuel, through a nozzle (notshown) connected to the fuel pipe carrying the diesel to the mixingchamber. More than one nozzle can be added to the fuel delivery pipe forthe capability of adding more than one blending agent to the base fuel.The nozzle is designed to disburse the blending agent into the flowingbase fuel. The flow rate of the blending agent is, determined by thefeed back signals to the system microprocessor 110 from the fuel flowsensor 50 and the engine speed.

An algorithm in the microprocessor software determines the volume ofblending agent to be delivered to the nozzle. An output signal from themicroprocessor to a proportional solenoid valve 25 controls the volumeof blending agent pumped to the nozzle. The low rate of the blendingagent is measured continuously by a flow meter prior to the nozzle. Theflow meter signal is used to verify that the flow rate matches thetheoretical value. The proportional solenoid valve 25 is adjustedaccordingly. The time base for the measurement and adjustment of systemparameters is on per second basis.

The pressure of the blending agent mass flow delivered to the nozzle ismeasured by a pressure transducer (not shown). This pressure ismaintained above a minimum set value to ensure that the mass flow ratehas enough energy to be thoroughly disbursed into the base diesel fuelflow.

Just down stream of the nozzle, the high speed paddle 35 comes intocontact with the mixture of the blending agent and the base diesel fuel.The shearing force from the high speed rotating paddle results in theblending agent being completely dispersed into the base diesel. Forliquid blending agents, diesel fuel emulsions are formed where microdroplets of the liquid blend agent are suspended in largervolumes/droplets of the base diesel fuel. The blend agent droplets willremain in suspension for a short period of time without the necessity toadd surfactants in order to maintain the phase separation. Theemulsion/blended fuel is to be injected into the combustion chamberprior to phase separation occurring. For fuel blends where the blendingagent is gaseous (eg. methane), the mixing chamber creates micro bubblesof gas that are entrained throughout the base diesel fuel.

A mixing chamber combines the water from the water feed 17 and thediesel oil from the diesel oil feed 15. As the water and diesel oilcombine, the mixture is subjected to an emulsification step usingemulsifier means 30 to form the components as an emulsified fuel feed.Depending on the type of diesel engine and other variables, up to about40% of the emulsion mixture is comprised of water; in more preferredembodiments, 5 to 35% of the emulsion volume is comprised of water andmore desirably, 10 to 30%. The emulsifier means may be any suitableagitation means capable of forming a non-stable oil-in-water emulsion,preferably of the type in which at least 90% of the droplets are lessthan 1 μm in diameter. Typically, the emulsifier means may be of a typesuch as a shear mixer (shown in FIG. 1) located in the mixing chamberand which shear mixer 35 is capable of having a speed of at least 2500to 6000 RPM. At such a shear mixing, a suitable non-stable fuel emulsionof a beneficial nature can be produced for use in the system of thepresent invention.

The emulsion is then fed to the diesel engine 40 by way of a feed line45 to the fuel injector pump (not shown) where the fuel pressure isincreased, after which it is directed to the individual combustionchamber fuel injectors; preferably, the mixing chamber is positioned inrelatively close proximity to the diesel engine 40 such that theemulsion does not substantially de-mulsify between the mixing chamber 30and the diesel engine 40. Thus, the length of feedline 45 is desirablyshort enough so that when relatively slow combustion levels of fuel areused the fuel emulsion mixture remains substantially intact.

In accordance with this invention, excess emulsified fuel is then fed tothe injectors (not shown) of the diesel engine 40. This feed systemincludes recovery means for the recovery of non-utilized or excess fuelfrom the injectors (not shown). To this end, the recovery system of thepresent invention includes a sensing means, and a means for recoveringand separating excess emulsified fuel.

During operation, the load of engine 40 determines the rate of fuelmixture being delivered to the injectors (not shown) in the engine 40. Asensing means 50 in conjunction with the engine load provides a signalto a controlling means 110 for the flow rate of the water from the watersource 20 to be adjusted according to the fuel flow rate in the engine40. Upon determining the appropriate conditions for adjusting the waterflow rate in the system, the controlling means 110 signals a valve 25 toopen or close accordingly. The excess emulsion fuel mixture not usedduring operation may then be fed through an outfeed line 60 which feedsthe excess emulsified fuel to a separating means 70.

The separating means 70 allows for the recovered non-combusted fuel toseparate into its component parts. Any suitable equipment for separatingwater from the fuel to obtain substantially pure component parts can beused; typically, separators such as centrifugal separators are known forthis purpose. From the separator 70, water is then fed back to the watersource 20 through a recovery feed line 90 and the diesel oil is fed backto the diesel oil source 10 through a separate recovery feed line 80whereby these components can be reused.

For many diesel engine technologies, up to 96% of the fuel flow to theinjectors is returned to the fuel tank, as this excess fuel servescoolant for the fuel injectors. Depending on the blending agent that isbeing used, it would be necessary under certain conditions to remove theagent from the fuel blend that is being returned to the fuel tank. Forexample, if water was being used as the blending agent 20, the fuelwould create operational problems in cold weather conditions, as thewater has the potential to phase separate and then freeze in the fueltank. Under these conditions, the water would be demulsified from thediesel fuel on the return to the fuel tank. This process is accomplishedby using techniques which will separate different liquids and gaseoussubstances based on the differences in thermal properties. The wasteheat from the engine exhaust provides the energy to separate the blendedsubstances. After separation, the base diesel fuel is returned to thefuel tank and the blending agent is recaptured and recycled through theemulsification/blending system.

The system control microprocessor 110 allows for the operator to inputthe quantity of blending agent to be added to the base fuel forspecified operating conditions. For example, if water is the blendingagent 20, then it would not be possible to achieve a condition of ratedengine horsepower with the diesel—water emulsion, as the energy contentavailable from the combustion of water is zero. For full powerconditions the operator would input zero percent blending agent whichwould result in 100% diesel fuel being delivered to the fuel injectors.

The continuous monitoring and adjustment of the fuel blend beingdelivered to the engine's 40 combustion chambers provides for theoptimization of the fuel combustion and exhaust emissions process forcold starting, particulate formation at part throttle and under highload, high speed conditions and oxides of nitrogen curing high load,high speed conditions and the reduction of Green House Gases throughboth life cycle CO₂ reductions and improved fuel efficiency.

Where the use of a surfactant is preferred, separate recovery means forthe surfactant component, for example, crude oil or hydrocarbons, mayalso be detected and the surfactant component may then be returned toits source of origin.

Those skilled in the art will appreciate that any type of conventionalsignal processor may be used for providing signals to the system andfurther details regarding the sensor will not be outlined herein.

It is therefore evident from this disclosure that an emulsified fuel canbe formed and recovered for re-use in the system. The present invention100 enables excess fluids such as diesel oil and water to be returned totheir points of origin and reused in the system without penalizingengine performance characteristics.

It is also understood by those skilled in the art to which the inventionpertains that the invention has been described by way of a detaileddescription of a preferred embodiment and departures from and variationsto this arrangement may be made without departing from the spirit andscope of the invention, as the same set out and characterized in theaccompanying claims.

1. In a fuel system for feeding fuel to a diesel engine, the improvementcomprising: means for variably feeding an excess of a non-stableemulsion of blending agent in diesel fuel to said diesel engine,recovery means for recovering excess fuel fed to said diesel engine, andseparating means associated with said recovery means for separating ofthe recovered non-combusted fuel into its component parts.
 2. The fuelsystem of claim 1, further including means for blending a plurality ofblending agents.
 3. The fuel system of claim 1 or 2, including anemulsifier means for forming a non-stable water in oil emulsion in whichat least 90% of the droplets are less than 1 um in diameter.
 4. Thesystem of claim 1, wherein said system comprises a water source, adiesel oil source and a mixing chamber having an agitation means forforming said non-stable emulsion mixture, said first and second sourcesinclude a signal means and a pump means.
 5. The system of claim 6,wherein said agitation means is a propeller capable of havingrevolutions of 2500 to 6000 RPM.
 6. The recovery system of claim 1,wherein said recovery means comprises an non-stable emulsification ofblending agent and diesel oil separating into its separate componentsand a recovery chamber having one or more channels.
 7. The recoverysystem of claim 6, wherein one of said channels recover diesel oil fromsaid non-stable emulsification of blending agent and diesel oil.
 8. Therecovery system of claim 1, wherein said system is an on-board system.9. A closed loop system for feeding fuel to a diesel engine comprising:the fuel system of claim 1 or 2, said closed loop including a source ofdiesel oil, a source of blending agent, valve means for controllingfluid flow from said source of blending agent, a mixing chamber havingagitation means for forming an emulsion mixture, a microprocessor meansfor controlling said valve, means and fluid flow a diesel engine, saidseparating means including a diesel return flow and a blending agentreturn flow, said blending agent return flow being operativelyassociated with said source of blending agent, and said diesel returnflow being associated with said source of diesel oil.
 10. The system ofclaim 9, wherein said blending agent source and said diesel oil sourcefurther include a signal means and a pump means.
 11. The system of claim10, wherein said agitation means is a propeller having revolutions of2500 to 6000 RPM.
 12. The closed loop system of claim 9 wherein there isfurther provided blending means for a plurality of blending agents. 13.The recovery system of claim 1, wherein said recovery means comprises annon-stable emulsification of water and diesel oil separating into itsseparate components and a recovery chamber having one or more channels.14. The recovery system of claim 13, wherein one of said channelsrecovers diesel oil from said non-stable emulsification of blendingagent and diesel oil.
 15. The recovery system of claim 13, wherein saidsystem is an on-board system.
 16. The closed loop system of claim 9,wherein said system is an on-board system.
 17. In a method of feedingfuel to a diesel engine in a closed loop system, the improvementcomprising the steps of: forming of a variable non-stable emulsioncomprised of a blending agent and a diesel fuel, feeding an excess ofsaid non-stable emulsion to a diesel engine, recovering excess amountsof said emulsion not combusted by said engine, and separating saidexcess amount into the component parts of said emulsion.